The total amount of goods and services demanded in the economy at a given overall price level and in a given time period. It is represented by the aggregate-demand curve, which describes the relationship between price levels and the quantity of output that firms are willing to provide. Normally there is a negative relationship between aggregate demand and the price level. Also known as "total spending".

According to Keynes, the classics saw the price system in a free economy as efficiently guiding the mutual adjustment of supply and demand in all markets, including the labor market. Unemployment could arise only because of a market imperfection--the intervention of the government or the action of labor unions--and could be eliminated through removing the imperfection. In contrast, Keynes shifted the focus of his analysis away from individual markets to the whole economy. He argued that even without market imperfections, aggregate demand (equal, in a closed economy, to consumption plus investment plus government expenditure) might fall short of the aggregate productive capacity...

In the News and Examples

Ricardo Reis of Columbia University talks with EconTalk host Russ Roberts about Keynesian economics in the classroom and in research. Reis argues that Keynesian models are a useful framework for helping undergraduates understand macroeconomic ideas of general equilibrium. More generally, Reis argues, Keynesian ideas remain influential in macroeconomic research, particularly among Neo-Keynesians. Reis discusses the lessons the economics profession and the world have learned from the Great Depression and suggests that those lessons have helped us manage the current crisis. The conversation closes with a discussion of whether economics is a science.

This ability of fiscal policy to affect output by affecting aggregate demand makes it a potential tool for economic stabilization. In a recession, the government can run an expansionary fiscal policy, thus helping to restore output to its normal level and to put unemployed workers back to work. During a boom, when inflation is perceived to be a greater problem than unemployment, the government can run a budget surplus, helping to slow down the economy. Such a countercyclical policy would lead to a budget that was balanced on average....

Effects of trying to boost the economy via aggregate demand during business cycles: Gross Domestic Product, from the Concise Encyclopedia of Economics

In the short run, in business cycles the Keynesian emphasis on demand is relevant and alluring. But heavy-handed reliance on "demand management" policies can distort market prices, generate major inefficiencies, and destroy production incentives. India since its independence and Peru in the eighties are classic examples of the destruction that demand management can cause. Other less developed countries like South Korea, Mexico, and Argentina have shifted from an emphasis on government spending and demand management to freeing up markets, privatizing assets, and generally enhancing incentives to work and invest. Rapid growth of GDP has resulted....

A Little History: Primary Sources and References

Keynes's General Theory revolutionized the way economists think about economics. It was pathbreaking in several ways, in particular because it introduced the notion of aggregate demand as the sum of consumption, investment, and government spending; and because it showed (or purported to show) that full employment could be maintained only with the help of government spending. Economists still argue about what Keynes thought caused high unemployment....

His second major contribution is his invention of what is called the IS-LM model, a graphical depiction of the argument John Maynard Keynes gave in his General Theory of Employment, Interest and Money (1936) about how an economy could be in equilibrium with less than full employment. Hicks published it in a journal article the year after Keynes's book was published. It seems safe to say that most economists became familiar with Keynes's argument by seeing Hicks's graph....

Advanced Resources

Steve Fazzari, of Washington University in St. Louis, talks with EconTalk host Russ Roberts about Keynesian economics. Fazzari talks about the paradox of thrift, makes the case for a government stimulus plan, and weighs the empirical evidence for a Keynesian worldview....

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The cuneiform inscription in the Liberty Fund logo is the earliest-known written appearance of the word "freedom" (amagi), or "liberty." It is taken from a clay document written about 2300 B.C. in the Sumerian city-state of Lagash.